1H-pyrazolo[1.5-b][1,2,4]triazole magenta couplers are disclosed in JP-A-59-171956 (the term "JP-A" as used herein means an "unexamined published Japanese patent application") and U.S. Pat. No. 4,540,654. These couplers are known to have excellent color reproducibility and give fast color images; they are also known to be easily produced. Various investigations have heretofore been made for improving the sensitivity and gradation of these couplers. For instance, couplers having a phenolic hydroxyl group in the molecule are disclosed in JP-A-61-65248 and U.S. Pat. No. 4,443,536; couplers having a sulfonamido group in the molecule are disclosed in JP-A-61-65246 and European Patent 176,804; couplers having two sulfonamido groups in the molecule are disclosed in JP-A-62-125349; and couplers having a sulfonyl group in the molecule are disclosed in JP-A-62-209460. However, silver halide photographic materials containing the couplers described in these patent publications have a problem in that their sensitivity lowers when they are stored for a long period of time. Silver halide photographic materials containing couplers described in JP-A-62-79451, U.S. Pat. No. 4,900,655 and JP-A-1-106055 where R.sub.5 is a substituted phenyl group also have the same problem.